Hydrocarbons, for example, oil, natural gas, and the like, may be obtained from a subterranean geologic formation by drilling a well that penetrates the hydrocarbon-bearing formation. Well treatment methods often are used to increase hydrocarbon production by using a treatment fluid to interact with a subterranean formation in a manner that ultimately increases oil or gas flow from the formation to the wellbore for removal to the surface.
Well treatment fluids, particularly those used in fracturing or those used in gravel packing operations, may contain a water or oil based fluid incorporating a thickening agent, normally a biomaterial or polymeric material. Such fracturing fluids often have a high viscosity during treatment of a subterranean formation to develop a desired fracture geometry and/or to carry proppant into a fracture with sufficient resistance to settling.
However, bacterial or fungal cells may be present in the treatment fluid. The bacterial or fungal cells may produce enzymes that degrade the biomaterial present in the treatment fluid for providing viscosity. As a result, the viscosity of the treatment fluid may decrease. Enzymes may also be employed as a breaker to reduce the viscosity of the fluid downhole for recovery of the fracturing fluid such that the fluid flows naturally through the proppant pack.